Basic Sensor Operations

Operation of Inductive Proximity Sensors

Sensing: The inductive proximity will sense all metals. The exact point at which a target will be detected is influenced
by the type of metal, its size and surface area.

STANDARD RANGE

Shielded: Can be mounted flush with metal surface.

EXTENDED RANGE

Non-shielded: Can NOT be mounted flush with metal surface

The two most common approach directions are axial (head-on)
and lateral (from the side). Detection occurs at the point where
the target first touches the envelope of the sensing curve. The curve
shown is for a standard target and must be corrected for other size
targets.

Correction Factors for Typical Target Materials

Based on Standard Size

Target Material

Corrective Factor

Steel 1020

1.00

430 Stainless

1.03

302 Stainless

.85

Brass

.50

Aluminum

.47

Copper

.40

Operation of Photo-Electric Sensors

Diffuse-Reflective

This type of sensor detects the reflection of transmitted light from the surface of an object. Shortest sensing
range of all photoelectric sensors.

Retro-Reflective

This type of sensor utilizes a special reflector to return the beam directed at it from the sensor. An object
between the sensor and reflector senses when the beam is interrupted. Medium sensing range.

Thru-Beam

Separate emitter and receiver provide maximum detection range and most positive type of sensing for opaque
objects. When an object interrupts the beam from emitter to receiver, the object is detected.

Operation of 2-Wire and 3-Wire Sensors

A/C 2 Wire NO

2-Wire Devices:

2-wire sensors are intended to be connected
tin series with the controlled load. Because these sensors derive
the power to energize their internal electronics through the load
they control, a minimum current is drawn through the load when the
sensor is in the open stat. This current is so small that it can
be ignored and will not turn on electro-mechanical devices such as
relays and solenoids. However, this current could be enough to operate
an electronic load. Cutler-Hammer's 2-wire sensors have the lowest
leakage current in the industry and are suitable for many electronic
loads.

A/C 3 wire NO/NC or DC PNP

3-WIRE DEVICES:

3-wire sensors derive their power directly
across the line and therefore have no current leakage to the load.

OPERATION OF LOGIC MODULES

On Delay

Adjustable delay between time object is sensed and time switch function occurs.

Off Delay

Adjustable delay between time object leaves sensing field & time switch transfers back to non-sensing state.

On & Off

Combination of Above.

Delayed Single
Shot

Adjusts length of time switch remains in "ON'
cycle after object is sensed regardless of length of time object
stays in sensing field. "ON" cycle can also be delayed
after object is first detected.